Abstract: The invention provides a jet mill which comprises a hollow disk-shaped turning and crushing chamber; a plurality (“m”) of crushing nozzles, to form turning flows by jetting a high pressure gas, in which the jetting ports are inclined to the peripheral wall side and disposed at the sidewall of the turning and crushing chamber; a plurality (“n”) of venturi nozzles, disposed at the side wall of the turning and crushing chamber, which leads materials to be crushed, in line with the high pressure gas; a solid and gas blending chamber which is formed at the upstream side of the venturi nozzles; a crushed material supplying portion communicating with the solid and gas blending chamber; a press-in nozzle disposed in the solid and gas blending chamber coaxially with the venturi nozzles; and an outlet, disposed at the upper part of the middle portion of the turning and crushing chamber, through which micro powder is discharged; wherein the dependency of materials to be crushed for collision with